Research on Imaging Method of Gas-Liquid Interface in Aerospace Propellant Tanks Based on Ultrasonic Tomography

Abstract Aerospace propellant tanks are subject to factors such as pressure disturbances, leading to uncertainty in the position of the internal liquid propellant and pressurized gas within the tank. The gas-liquid distribution within the tank reflects the working state of the propellant tank, affecting the timing of pressure relief, overall attitude control, and the measurement of propellant remaining under high-pressure conditions. The measurement of the gas-liquid distribution state is crucial for the normal operation of spacecraft. Existing methods are difficult to apply in spacecraft tank scenarios due to their requirements for the number or volume of sensors. This paper proposes a gas-liquid distribution reconstruction method based on ultrasonic tomography for spacecraft tank measurement scenarios. It investigates the priority back projection method, elliptical reflection method, and local curvature reconstruction method for gas-liquid interface based on transmitted signals, elliptical reflection signals, and echo signals, respectively. The image is processed based on the prior characteristics of the gas-liquid distribution material field, with the introduction of morphological image processing methods. Experimental results show that in small tank measurement scenarios, the cross-sectional gas holdup error can be within 3%, and the minimum positioning error of the gas-liquid interface is 2.21 mm.